Hanna Alkalinity Checker Reading High??

[ReeferMadness99]

Does anyone using the Hanna Alkalinity Checker have high results? My Checker is showing a dkh of 9.4 while my Elos test kit shows 7.5. I've done both tests multiple times and get the same results.

 

[Widdy]

http://www.advancedaquarist.com/2011/8/review

 

[ReeferMadness99]

Thanks for the read Steve! How disappointing. The whole point of getting the Hanna Checker was to get a more accurate reading than just eyeballing the color shift of titration tests. I guess thats out the window!

Boomer - I found an older thread where you said that a correction of -18% of the Hanna's readings proved to give a more accurate result in SW with normal pH. Is this still true? If so, then it would be fairly accurate because that would bring my Hanna reading down to 7.7 which is very much in line with the Elos test.

 

[Widdy]

No problem, Felix. Sorry, didn't have much to contribute as I don't own one. Just remembered Boomer's post http://www.manhattanreefs.com/forum/chemistry/103282-alk-readings.html

 

[ReeferMadness99]

No problem, Felix. Sorry, didn't have much to contribute as I don't own one. Just remembered Boomer's post http://www.manhattanreefs.com/forum/chemistry/103282-alk-readings.html

Yeah, I read that one too. It seemed to end a little vague as Boomer said something about misreading and correcting himself. I'm just not sure if his 18% correction factor still held some decent truth.

 

[Boomer]

That is correct reefer. I will write up a better answer tomorrow which will not give you guys much hope

 

[ReeferMadness99]

Well, as long as its a consistent correction factor then it works for me! Thanks!

 

[allenjj]

Evaluations

Great report Boomer. Have you compared their other test equipment to more rigorous standards? I have been considering a more expensive bench type piece of equipment, but your phosphate evaluation suggests the more inexpensive Hanna might be reasonable.

 

[Boomer]

I'm visiting in Texas and my buddies monitor went out tonight. I will try again tomorrow. I will not do this on a phone.

 

[Boomer]

OK, this is what happen. Dana did not use seawater stds for testing ALk. That means his HACH plots are ~ 10% low. If we add that 10 % to the HACH and look at the HANNA plots the HANNA is on avg is ~ 18 % to high. So, that means take the HANNA reading x .82.


Ex.

HANNA reads 200 ppm

200 x .82 = ~164 ppm corrected ruffly to fit our target range. Look at the plot where it is 200 ppm on the HACH, add 10 % = 220. The HANNA is ~ 265 ppm, a 45 ppm off-set.

265 x .82 = 217.3 ppm close to that 220 ppm

This NOT how we should have to do things For me, after talking to Habib, the Sailfert should be our ref std till shown otherwise. I will add, Alk is NOT an easy measurement in seawater. If using a Salifert you need to follow the instructions Exactly to get the proper reading.

 

[ReeferMadness99]

Thanks for the clarification Boomer. No, its not ideal to have to factor in such a high correction, but for the sake of getting a clear digital ppm reading as opposed to eyeballing a color shift (which by the way, only gets you .5 dkh at a time), I would still rather use the Hanna.

I'm trying to set my dosing pump to as exact measurements as possible. With a titration test kit, color changes within .5 dkh could have a devastating effect when your off by .3 or .4 within the shift. Compound that over time when your running a dosing pump and you could end up with your Alkalinity being off my 2-3 dkh over the course of 1 week or 2 if you don't test. This is what I'm trying to avoid so I like the digital reading of the Hanna. So far after 3 days of testing, My readings have been 169, 167, 166, so my dosing pump settings are doing the proper amounts to keep things very stable.

Thanks again Boomer!

 

[Boomer]

You bet let me know how it works.